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3B · Chapter 13 · exam

Chapter practice examination

Original untimed practice examination. Not a secure or official placement test.

Original untimed practice examination. Not a secure or official placement test. Solutions are available as revealable feedback and in a separate complete answer key. No answer submissions or accounts are required.

Assessment · 24 questions

Questions

Show your thinking; use diagrams when they help. Do not open solutions during your first attempt.

  1. A1

    A student answers the following question with “49 square units; 28 units”. Explain whether the answer is correct, then solve the question and justify your answer. Original question: A 8-by-6 rectangle has what area and what perimeter? Include units. (3 points)

    Reveal explanation

    Answer: 48 square units; 28 units

    The suggested answer is not correct. Area counts square units: 8 × 6 = 48. Perimeter counts the boundary: 2(8+6) = 28. They have different units.

    Scoring: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  2. A2

    A 8-by-4 rectangle has what area and what perimeter? Include units. (3 points)

    Reveal explanation

    Answer: 32 square units; 24 units

    Area counts square units: 8 × 4 = 32. Perimeter counts the boundary: 2(8+4) = 24. They have different units.

    Scoring: 1 point for area, 1 for perimeter, 1 for both appropriate units.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  3. A3

    A tiled mat is 3 square units across and 5 square units down. How many unit squares cover it? (2 points)

    Reveal explanation

    Answer: 15 square units

    There are 5 rows of 3 equal square units: 3 × 5 = 15 square units.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  4. A4

    A rectangular fence is 4 cm long and 4 cm wide. What length of edging goes all the way around? (2 points)

    Reveal explanation

    Answer: 16 cm

    Walk along every outer edge once: 4 + 4 + 4 + 4 = 16 cm.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  5. A5

    A student answers the following question with “16 square units”. Explain whether the answer is correct, then solve the question and justify your answer. Original question: A rectangular garden covers 3 rows of 5 equal unit squares. Find its area. (3 points)

    Reveal explanation

    Answer: 15 square units

    The suggested answer is not correct. There are 3 rows of 5 equal square units: 5 × 3 = 15 square units.

    Scoring: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  6. A6

    A rectangle measures 7 cm by 3 cm. What is its perimeter? (2 points)

    Reveal explanation

    Answer: 20 cm

    Walk along every outer edge once: 7 + 3 + 7 + 3 = 20 cm.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  7. A7

    A tiled mat is 5 square units across and 4 square units down. How many unit squares cover it? (2 points)

    Reveal explanation

    Answer: 20 square units

    There are 4 rows of 5 equal square units: 5 × 4 = 20 square units.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  8. A8

    A rectangle is 7 unit squares across and 6 unit squares down. What is its area? (2 points)

    Reveal explanation

    Answer: 42 square units

    There are 6 rows of 7 equal square units: 7 × 6 = 42 square units.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  9. A9

    A student answers the following question with “25 square units”. Explain whether the answer is correct, then solve the question and justify your answer. Original question: A rectangle is 8 unit squares across and 3 unit squares down. What is its area? (3 points)

    Reveal explanation

    Answer: 24 square units

    The suggested answer is not correct. There are 3 rows of 8 equal square units: 8 × 3 = 24 square units.

    Scoring: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  10. A10

    A rectangle measures 8 cm by 5 cm. What is its perimeter? (2 points)

    Reveal explanation

    Answer: 26 cm

    Walk along every outer edge once: 8 + 5 + 8 + 5 = 26 cm.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  11. A11

    A rectangular garden covers 3 rows of 7 equal unit squares. Find its area. (2 points)

    Reveal explanation

    Answer: 21 square units

    There are 3 rows of 7 equal square units: 7 × 3 = 21 square units.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  12. A12

    A rectangle measures 6 cm by 5 cm. What is its perimeter? (2 points)

    Reveal explanation

    Answer: 22 cm

    Walk along every outer edge once: 6 + 5 + 6 + 5 = 22 cm.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  13. A13

    A student answers the following question with “25 square units”. Explain whether the answer is correct, then solve the question and justify your answer. Original question: A rectangle is 6 unit squares across and 4 unit squares down. What is its area? (3 points)

    Reveal explanation

    Answer: 24 square units

    The suggested answer is not correct. There are 4 rows of 6 equal square units: 6 × 4 = 24 square units.

    Scoring: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  14. A14

    A 5-by-5 rectangle has a 1-by-2 corner removed. Find the remaining area in square units. (2 points)

    Reveal explanation

    Answer: 23 square units

    Whole rectangle: 5 × 5 = 25. Missing corner: 1 × 2 = 2. Remaining: 25 − 2 = 23.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  15. A15

    A tiled mat is 4 square units across and 6 square units down. How many unit squares cover it? (2 points)

    Reveal explanation

    Answer: 24 square units

    There are 6 rows of 4 equal square units: 4 × 6 = 24 square units.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  16. A16

    A rectangular garden covers 6 rows of 4 equal unit squares. Find its area. (2 points)

    Reveal explanation

    Answer: 24 square units

    There are 6 rows of 4 equal square units: 4 × 6 = 24 square units.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  17. A17

    A student answers the following question with “17 cm”. Explain whether the answer is correct, then solve the question and justify your answer. Original question: A rectangular fence is 5 cm long and 3 cm wide. What length of edging goes all the way around? (3 points)

    Reveal explanation

    Answer: 16 cm

    The suggested answer is not correct. Walk along every outer edge once: 5 + 3 + 5 + 3 = 16 cm.

    Scoring: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  18. A18

    A rectangular garden covers 4 rows of 5 equal unit squares. Find its area. (2 points)

    Reveal explanation

    Answer: 20 square units

    There are 4 rows of 5 equal square units: 5 × 4 = 20 square units.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  19. A19

    A rectangle is 6 unit squares across and 2 unit squares down. What is its area? (2 points)

    Reveal explanation

    Answer: 12 square units

    There are 2 rows of 6 equal square units: 6 × 2 = 12 square units.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  20. A20

    A 5-by-3 rectangle has what area and what perimeter? Include units. (3 points)

    Reveal explanation

    Answer: 15 square units; 16 units

    Area counts square units: 5 × 3 = 15. Perimeter counts the boundary: 2(5+3) = 16. They have different units.

    Scoring: 1 point for area, 1 for perimeter, 1 for both appropriate units.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  21. A21

    A student answers the following question with “17 cm”. Explain whether the answer is correct, then solve the question and justify your answer. Original question: A rectangular fence is 6 cm long and 2 cm wide. What length of edging goes all the way around? (3 points)

    Reveal explanation

    Answer: 16 cm

    The suggested answer is not correct. Walk along every outer edge once: 6 + 2 + 6 + 2 = 16 cm.

    Scoring: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  22. A22

    A 3-by-3 rectangle has a 2-by-1 corner removed. Find the remaining area in square units. (2 points)

    Reveal explanation

    Answer: 7 square units

    Whole rectangle: 3 × 3 = 9. Missing corner: 2 × 1 = 2. Remaining: 9 − 2 = 7.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

    Each visible square is 1 square unit.
    Square-unit grid; count only visible squares without gaps or overlap.
  23. A23

    A student says a rectangle with area 16 square units must have perimeter 16 units. Explain why this is not generally true using a 4-by-4 example. (3 points)

    Reveal explanation

    Answer: Perimeter 16 units

    The area is 4 × 4 = 16 square units, but its perimeter is 2 × (4+4) = 16 units. Area and perimeter measure different things.

    Scoring: 1 point for the correct claim; 1 for a mathematical justification; 1 for a clear diagram, example, or relevant calculation when applicable.

  24. A24

    A 3-by-4 rectangle and a 1-by-12 rectangle have the same area. Must they have the same perimeter? (3 points)

    Reveal explanation

    Answer: No

    Both areas are equal, but different side dimensions usually give different boundary lengths.

    Scoring: 1 point for the correct claim; 1 for a mathematical justification; 1 for a clear diagram, example, or relevant calculation when applicable.

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